Fresnel lens in a finder optical system

摘要

A Fresnel lens provided in the finder of a camera includes a central portion through which an optic axis passes, and a plurality of annular portions spaced apart from the central portion and disposed concentrically. The central portion and the plurality of annular portions have their respective focal lengths. The focal length of the central portion is shorter than the focal length of one of the annular portions which is remotest from the optic axis.